Ionomeric silicone thermoplastic elastomers

ABSTRACT

This invention relates to thermoplastic elastomers comprising at least one silicone ionomer. These thermoplastic elastomers may be reprocessed and/or recycled.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a U.S. divisional application of U.S. application Ser. No.12/809,610, which was a national stage filing under 35 U.S.C. §371 ofPCT Application No. PCT/US08/87327 filed on 18/DEC/2008, which claimedthe benefit of U.S. Provisional Patent Application No. 61/015,697 filed21/DEC/2007 under 35 U.S.C. §119 (e).

BACKGROUND OF THE INVENTION

This invention relates to thermoplastic elastomers comprising at leastone silicone ionomer. Ionomers as defined herein are polymers in whichthe bulk properties are governed by ionic interactions in discreteregions of the material (i.e., ionic aggregates). These predominantlynonpolar macromolecules contain ionic groups as part of the chain,usually at levels less than 15 mol %. Broad literature exists on organicionomers. Phase segregation of the ionic groups from the bulk of thepolymer results in the formation of a second phase, termed ionomericaggregates. A combination of the difference in solubility parameterbetween the ionic and siloxane phase and the strong ionic and coordinatebonding formed accounts for the formation of these aggregates.

According to the Eisenberg-Hird-Moore (EHM) model, the ionomericaggregates occupy a region of about 6 Å and affect a region of about 30Å resulting in a state of reduced polymer mobility. The small size ofthese ionomeric aggregates (less then the wavelength of light) ensuresthe transparency of these materials. The aggregation of ionic groups,also termed “multiplets”, can impart physical crosslinks to the basepolymer, greatly modifying the viscoelastic properties of the resultingpolymer. In addition, since the crosslinks are physical crosslinks theymay be broken up by heating or dissolution and therefore the materialsthey form may be recycled and/or reformed.

Generally, silicone polymers can form either thermoset or thermoplasticelastomers. With a thermoset elastomer, the silicone polymers arechemically crosslinked. These types of crosslinks are not reversible andtherefore thermoset elastomers are not recyclable. Thermoplasticelastomers are polymeric materials which possess both plastic andrubbery properties. Thermoplastic elastomers can be processed usingconventional polymer processing methods like extrusion, blow molding,melt spinning, etc. which are challenging for thermosetting systems.They have elastomeric mechanical properties but, unlike conventionalthermoset rubbers, they can also be re-processed at elevatedtemperatures. This re-processability is a major advantage ofthermoplastic elastomers over chemically crosslinked rubbers since itallows recycling of fabricated parts and results in a considerablereduction of scrap. With the increased focus on the environment it isvery important to develop materials that can be recycled and/orreprocessed when no longer needed.

BRIEF SUMMARY OF THE INVENTION

The present invention is a thermoplastic elastomer comprising at leastone silicone ionomer having an average Formula (1)(X_(v)R_(3-v)SiO_(1/2))_(a)(X_(w)R_(2-w)SiO_(2/2))_(b)(X_(y)R_(1-y)SiO_(3/2))_(c)(SiO_(4/2))_(d)where each R is an independently selected monovalent alkyl group or arylgroup, each X is independently selected from a monovalent alkyl group,aryl group and a carboxy functional group having a Formula (2)

-G-COOZ, where G is a divalent spacer group having at least 2 spacingatoms, each Z is independently selected from hydrogen or a cationindependently selected from alkali metal cations, alkali earth metalcations, transition metal cations, and metal cations, v is 0 to 3, w is0 to 2, y is 0 to 1, 0≦a≦0.9; 0≦b<1; 0≦c≦0.9, 0≦d<0.3 and a+b+c+d=1,provided that on average there is at least 0.002 mole carboxy functionalgroups per silicon atom and at least 10 mole percent of the Z groups ofthe carboxy functional group are an independently selected cation.

The inventors have determined that certain silicone ionomers can formphysical crosslinks which increase viscosity and can impart elastomericbehavior. Unlike materials having chemical crosslinks, materialscomprising silicone ionomers may be recycled and/or reprocessed when nolonger needed. An object of the present invention is to describethermoplastic elastomers comprising at least one silicone ionomer.Another object of the present invention is to describe a method ofsealing or bonding two substrates using the thermoplastic elastomers asa hot melt material comprising at least one silicone ionomer or a blendof silicone ionomers.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1: Storage modulus (G′) of polydimethylsiloxanes bearing pendantcarboxy acid functional radicals, neutralized with different levels ofLithium counter-ions; x and y refer to the Formula(Me₃SiO_(1/2))_(0.018)(MeR′SiO_(2/2))_(x)(MeR″SiO_(2/2))_(y)(Me₂SiO_(2/2))_(0.95)with R′—(CH₂)₁₀—COOH and R″—(CH₂)₁₀—COO⁻L⁺ measurements were performedunder oscillatory shear using small sinusoidal strain (<5%).

FIG. 2: Loss modulus (G″) of polydimethylsiloxanes bearing pendantcarboxy acid functional radicals, neutralized with different levels ofLithium counter-ions; x and y refer to the Formula(Me₃SiO_(1/2))_(0.018)(MeR′SiO_(2/2))_(x)(MeR″SiO_(2/2))_(y)(Me₂SiO_(2/2))_(0.95)with R′—(CH₂)₁₀—COOH and R″—(CH₂)₁₀—COO⁻Li⁺; measurements were performedunder oscillatory shear using small sinusoidal strain (<5%).

FIG. 3: Tensile properties at 25° C. measured at 2 inch/min strain speedcomparing the PDMS ionomer and rubber from Example 7.

DETAILED DESCRIPTION OF THE INVENTION

In the present invention, each silicone ionomer which is useful formaking a thermoplastic elastomer has an average Formula (1)(X_(v)R_(3-v)SiO_(1/2))_(a)(X_(w)R_(2-w)SiO_(2/2))_(b)(X_(y)R_(1-y)SiO_(3/2))_(c)(SiO_(4/2))_(d),where each R is an independently selected monovalent alkyl group or arylgroup, each X is independently selected from a monovalent alkyl group,aryl group and a carboxy functional group having a Formula (2) -G-COOZ,where G is a divalent spacer group having at least 2 spacing atoms, eachZ is independently selected from hydrogen or a cation independentlyselected from alkali metal cations, alkali earth metal cations,transition metal cations, and metal cations, v is 0 to 3, w is 0 to 2, yis 0 to 1, 0≦a≦0.9; 0≦b<1; 0≦c≦0.9,0≦d<0.3 and a+b+c+d=1, provided that on average there is from 0.002 to0.5 moles carboxy functional groups per silicon atom and at least 10mole percent of the Z groups of the carboxy functional group are anindependently selected cation.

Each R is an independently selected monovalent alkyl group or arylgroup. Alternatively, each R is an independently selected alkyl grouphaving 1 to 10 carbon atoms or an aryl group having 6 to 20 carbonatoms. Alternatively, each R is an independently selected methyl orphenyl group. Alternatively, each R is methyl. Examples of useful alkylgroups include methyl, ethyl, n-propyl, iso-propyl, n-butyl, isobutyl,tert-butyl, n-pentyl, iso-pentyl, neopentyl and tert-pentyl; hexyl, suchas the n-hexyl group; heptyl, such as the n-heptyl group; octyl, such asthe n-octyl and isooctyl groups and the 2,2,4-trimethylpentyl group;nonyl, such as the n-nonyl group; decyl, such as the n-decyl group;cycloalkyl radicals, such as cyclopentyl, cyclohexyl and cycloheptylradicals and methylcyclohexyl radicals Examples of aryl groups includephenyl, naphthyl; o-, m- and p-tolyl, xylyl, ethylphenyl, and benzyl.

In Formula (1), subscript v is 0 to 3, w is 0 to 2, and y is 0 to 1.Further, 0≦a≦0.9, alternatively 0<a≦0.7, alternatively 0<a≦0.5; 0≦b<1;alternatively 0.5≦b<1, alternatively 0.7≦b<1; 0≦c≦0.9, alternatively0≦c≦0.5, alternatively 0≦c≦0.3; 0≦d≦0.3; alternatively 0≦d≦0.2,alternatively 0≦d≦0.1, and a+b+c+d=1. A person skilled in the art wouldknow that the siloxane units in Formula 1 such as(X_(v)R_(3-v)SiO_(1/2)) are often referred to as a M unit,(X_(w)R_(2-w)SiO_(2/2)) are often referred to as a D unit,(X_(y)R_(1-y)SiO_(3/2)) are often referred to as a T unit, and(SiO_(4/2))_(d), are often referred to as a Q unit.

Each X group of Formula (2) is independently selected from a monovalentalkyl group, aryl group and a carboxy functional group having theFormula (2) -G-COOZ. With respect to Formula (2), each G is a divalentspacing group having at least 2 spacing atoms, alternatively G is adivalent hydrocarbon group having at least 2 carbon atoms or a divalenthydrocarbonoxy group having at least 2 carbon atoms. Alternatively, G isan alkylene group having 2 to 20 carbon atoms. The divalent hydrocarbongroup can be illustrated by alkylene groups selected from —(CHR²)_(s)—where s has a value of 2 to 20 and R² is hydrogen or a group defined byR above, such as —CH₂CH₂—, —CH₂CH(CH₃)—, —CH₂CH(CH₃)CH₂—,—CH₂CH₂CH(CH₂CH₃)CH₂CH₂CH₂—. The divalent hydrocarbon group can also beillustrated by arylene groups selected from —(CH₂)_(u)C₆H₄—,—CH₂CH(CH₃)(CH₂)_(u)C₆H₄—, and —(CH₂)_(t)C₆H₄(CH₂)_(u)— where t has avalue of 1 to 20 and u has a value of 0 to 10. The divalenthydrocarbonoxy group can be illustrated by —OCH(R)(CH₂)_(t)— and—OCH(CH₃)(CH₂)_(t)— where R and t is as described above.

With respect to Formula (2), each Z is hydrogen or a cationindependently selected from alkali metals, alkali earth metals,transition metals and metals. Alternatively, each cation isindependently selected from Li, Na, K, Cs, Mg, Ca, Ba, Zn, Cu, Ni, Ga,Al, Mn, and Cr. Alternatively, each cation is independently selectedfrom Li, Na, K, Zn, Ni, Al, Mn, Mg. Alternatively, each cation isindependently selected from Li, Na, K, Zn, Al, Mg. One skilled in theart would understand that a cation derived from a certain metal can havedifferent valences depending on the number of associated ligands. Forexample, Mn²⁺ and Mn³⁺ neutralized carboxylic acid functional siloxaneionomers can be prepared depending on the manganese neutralization agentused.

Generally, on average there are from 0.002 to 0.5 mole carboxyfunctional groups per silicon atom. Alternatively, on average there arefrom 0.01 to 0.4 mole carboxy functional groups per silicon atom.Alternatively, on average there are 0.02 to 0.2 mole carboxy functionalgroups per silicon atom.

Further, at least 10 mole percent of the Z groups of the carboxyfunctional group are an independently selected cation. Alternatively, atleast 50 mole percent of the Z groups of the carboxy functional groupare an independently selected cation. Alternatively, at least 75 molepercent of the Z groups of the carboxy functional group are anindependently selected cation. Alternatively, 100 mole percent of the Zgroups of the carboxy functional group are an independently selectedcation. The carboxy functional group may be present in any of the M, Dor T siloxane units described by subscripts a, b, and c. Alternatively,the carboxy functional group may be present in the M and D siloxaneunits described by subscripts a and b.

The degree of polymerization (dp) of the silicone ionomer can varydepending on the desired properties. Alternatively, the dp of thesilicone ionomers can be from 10 to 10,000; alternatively 20 to 5,000;alternatively 40 to 5,000.

Another embodiment of the present invention is a thermoplastic elastomerconsisting essentially of at least one silicone ionomer as describedabove.

In addition to the silicone ionomer, it may also be useful, depending onthe desired application for the thermoplastic elastomer, to add at leastone MQ resin. MQ resins are macromolecular polymers comprised primarilyof R¹ ₃ SiO_(1/2) and SiO_(4/2) units (the M and Q units, respectively)where R¹ is a functional or nonfunctional, substituted or unsubstitutedmonovalent radical. Alternatively, R¹ is methyl or phenyl. Those skilledin the art will appreciate that such resins may also include a limitednumber of R¹ ₂ SiO_(2/2) and R¹SiO_(3/2) units, respectively referred toas D and T units. As used herein, the term “MQ resin” means that, onaverage, no more than about 20 mole percent of the resin molecules arecomprised of D and T units. Generally, when an MQ resin is added up to80 weight parts based on 100 weight parts of the silicone ionomer may beused. Alternatively, from 10 to 70 weight parts based on 100 weightparts of the silicone ionomer may be used. Alternatively, from 30 to 65weight parts on the same basis may be used.

MQ resins are commercially available or made by known processes. Forexample, U.S. Pat. No. 2,814,601 to Currie et al., Nov. 26, 1957, whichis hereby incorporated by reference, discloses that MQ resins can beprepared by converting a water-soluble silicate into a silicic acidmonomer or silicic acid oligomer using an acid. When adequatepolymerization has been achieved, the resin is end-capped withtrimethylchlorosilane to yield the MQ resin. Another method forpreparing MQ resins is disclosed in U.S. Pat. No. 2,857,356 to Goodwin,Oct. 21, 1958, which is hereby incorporated by reference. Goodwindiscloses a method for the preparation of an MQ resin by thecohydrolysis of a mixture of an alkyl silicate and a hydrolyzabletrialkylsilane organopolysiloxane with water. MQ resins have alsoreportedly been prepared by cohydrolysis of the corresponding silanes orby silica hydrosol capping methods known in the art. MQ resins used mayalso be prepared by the silica hydrosol capping processes of Daudt, etal., U.S. Pat. No. 2,676,182;

Another optional ingredient is a filler. The filler may be added in anamount up to 60 weight parts based on 100 weight parts of the siliconeionomer. Alternatively, from 0 to 50 weight parts based on 100 weightparts of the silicone ionomer may be used. Alternatively, from 5 to 30weight parts on the same basis may be used. Fillers useful in theinstant invention may be exemplified by, but not limited to, inorganicmaterials such as pyrogenic silica, precipitated silica and diatomaceoussilica, ground quartz, aluminum silicates, mixed aluminum and magnesiumsilicates, zirconium silicate, mica powder, calcium carbonate, glasspowder and fibers, titanium oxides of the pyrogenic oxide and rutiletype, barium zirconate, barium sulphate, barium metaborate, boronnitride, lithopone, the oxides of iron, zinc, chrome, zirconium, andmagnesium, the different forms of alumina (hydrated or anhydrous),graphite, lamp black, asbestos, and calcined clay and organic materialssuch as the phthalocyamines, cork powder, sawdust, synthetic fibers andsynthetic polymers (polytetrafluoroethylene, polyethylene,polypropylene, polystyrene and polyvinyl chloride). The filler may be ofa single type or mixtures of several types.

In general, small amounts of additional ingredients may also be added tothe compositions of this invention. For example, antioxidants, pigments,stabilizers, moisture scavengers, diluents, carriers, and others, may beadded as long as they do not materially alter the requirementsstipulated herein.

The flow temperature corresponds to the temperature at which thematerial has the ability to conform to any shape. Modifying the flowtemperature is useful both for processing the material and forapplications like hot melt. Generally, the flow temperature determinesthe minimum temperature needed to process the material and at the sametime the maximum temperature of use before the formed shape loses itsintegrity.

The silicone ionomers useful to make the thermoplastic elastomers of theinvention can be made by hydrosilylating a siloxane polymer bearinghydrogen groups (SiH functionality) with protected undecylenic acid(e.g. trimethylsilylated undecylenic acid) in solution. A platinumcatalyst may be used to aid the reaction. After stripping the polymerfrom solvent, the siloxane polymer bearing protected undecylenic acidgroups is converted into the carboxylic acid functional derivatizedmaterial by deprotection with methanol. To obtain the correspondingionomeric silicones, the carboxylic acid functional siloxane isneutralized with metal salts, usually metal acetylacetonates, beingmindful of the valency of the specific metal counter-ion of interest.For example, for a divalent counter-ion, a molar ratio of 1 to 2 metalsalt to carboxylic acid should be used to attain 100% neutralization.After formation of the ionomeric siloxane, the solvent is stripped undervacuum to obtain a solid material with thermoplastic elastomericproperties. Optional ingredients can be added before the stripping stepor afterwards by using an appropriate co-solvent. Alternatively,extrusion at temperatures above the flow temperature of the ionomericsiloxane can be used to introduce optional ingredients without the useof solvent.

To prepare or recycle a finished part or to seal or bond two substrates,the silicone ionomer needs to be heated above its flow temperature,which will be specific to the molecular weight, ion content, type ofcounter-ion and extent of neutralization of the silicone ionomer. Thestrength of the physical cross-links introduced through the ionicaggregates can be modified by changing the metal counter-ion type. Forexample changing the metal counter-ion from Na⁺ to Mg⁺⁺ will increasethe flow temperature. In addition, increasing the metal ionneutralization extent increases the strength of the physical crosslinksand therefore also increases the flow temperature. In this way, flowtemperatures can be adjusted.

Precursor linear polydimethylsiloxanes (PDMS) are typically flowableliquids at temperatures as low as −80° C. Conversion to a metalneutralized silicone ionomer can increase the flow temperaturedramatically, for example for the linear polydimethylsiloxanes from −80°C. to 300° C. Depending on the molecular weight, ion content, type ofcounter-ion and extent of neutralization, the flow temperature of asilicone ionomer can be at least 0° C. Alternatively, the flowtemperature of a silicone ionomer can range from 0° C. to 300° C.,alternatively from 100° C. to 300° C., alternatively from 100° C. to250° C.

The storage moduli of silicone ionomers at room temperature are from 10²Pa to 10⁸ Pa, alternatively from 10³ Pa to 10⁸ Pa, alternatively from10⁴ to 10⁷ Pa. As a reference, a typical high molecular weightpolydimethylsiloxane (termed ‘gum’) will have a storage modulus in the10³ to 10⁴ Pa range, considerably lower than what can be achieved withsilicone ionomers. A glassy material, for example a polydimethylsiloxaneat temperature below its glass transition (below −125° C.) has a storagemodulus of 10⁹ Pa.

In addition to heat, one may use solvent to recycle the thermoplasticelastomers of the present invention. A combination of an aromatichydrocarbon solvent like toluene, xylene and a polar alcohol likemethanol, preferably in a 9/1 volume ratio should be used. The aromaticsolvent ensures dissolution of the siloxane backbone, while the polaralcohol is needed to break the ionic aggregates and dissolve thesilicone ionomer.

The thermoplastic elastomers of this invention find utility in many ofthe same applications as now being served by silicone pressure sensitiveadhesives (PSAs) and/or organic or silicone hot melt adhesives,particularly in such thermoplastic industries as automotive, electronic,construction, space and medical. In addition, the thermoplasticelastomers may be used for personal care products, for example as agellant.

When the thermoplastic elastomers of the present invention are used ashot melt PSAs, they may be applied to various substrates by techniquescurrently employed for dispensing other type of hot melt materials(e.g., hot melt gun, spraying, extrusion, spreading via heated draw-downbars, doctor blades or calendar rolls). The common factor in thesemethods is that the composition is heated to a temperature sufficient toinduce flow before application. Upon cooling to ambient conditions, thecompositions of the present invention range from tacky low modulusadhesives to non-tacky, non-slump PSAs which may be used to bondcomponents or substrates to one another. Bonding is imparted not onlythrough the transition from a flowable mass to a rubbery elastomer butcan also take place through strong ionomer—substrate interactions suchas ionomer—silanol interactions in case of glass substrates. Thesilicone ionomers deliver green strength by passing through the ionomertransition upon cooling, so sealed structures can be immediately handledwithout risking the integrity of the seal or bond.

Unlike other PSAs or hot melts, after the desired components are bondedwith the thermoplastic elastomer of the invention, the present inventiononly requires that the temperature cool down for it to harden, there isno curing time. Rather, upon cooling, the ionic aggregate re-form to anelastomer. With other PSAs or hot melts, the time required forcompletion of the cure process ranges from about a day to more than amonth, depending for example, upon the catalyst type, catalyst level,temperature and humidity.

Another embodiment of the present invention is a method of sealing orbonding at least two substrates comprising the steps of

(i) heating at least one thermoplastic elastomer comprising at least onesilicone ionomer so that it flows;

(ii) applying to a first substrate, the heated thermoplastic elastomer;

(iii) positioning a second substrate so the heated thermoplasticelastomer effects a seal therebetween or causes the first substrate tobond to the second substrate before the heated thermoplastic elastomercools down;

(iv) allowing the heated thermoplastic elastomer to cool down.

The temperature to which the thermoplastic elastomer needs to be heatedwill vary depending on the type of cation, mole fraction of the cationand the extent of neutralization present, however, it is necessary thatthe temperature be high enough so the thermoplastic elastomer flows. Anysubstrate may be used including glass, aluminum, steel, etc.

EXAMPLES

The following examples are included to demonstrate preferred embodimentsof the invention. It should be appreciated by those of skill in the artthat the techniques disclosed in the examples which follow representtechniques discovered by the inventor to function well in the practiceof the invention, and thus can be considered to constitute preferredmodes for its practice. However, those of skill in the art should, inlight of the present disclosure, appreciate that many changes can bemade in the specific embodiments which are disclosed and still obtain alike or similar result without departing from the spirit and scope ofthe invention. All parts and percentages in the examples are on a weightbasis and all measurements were obtained at 25° C., unless indicated tothe contrary.

Test Methods:

²⁹Si Nuclear Magnetic Resonance Spectroscopy (NMR)

Ionomer samples for NMR analysis were prepared by introducingapproximately 4 grams of sample into a vial and diluting withapproximately 4 grams of 0.04M Cr(acac)3 solution in CDCl3. Samples weremixed and transferred into a silicon-free NMR tube. Spectra wereacquired using a Varian Mercury 400 MHz NMR.

Rheology Measurements (Storage Modulus, Loss Modulus, ViscosityMeasurements):

A TA Instruments ARES-RDA (2KSTD standard flexular pivot springtransducer) with forced convection oven was used to measure the storagemodulus (G′) and loss modulus (G″) of siloxane ionomers. Test specimens(typically 8 mm wide, 0.1 mm thick) were loaded in between parallelplates and measured using small strain oscillatory rheology whileramping the temperature in a range from −120° C. to 250° C. at 2° C./min(frequency 1 Hz). Viscosity of flowable liquids were measured using thesame instrument in steady shear mode at different temperatures,typically using a 25 mm cone and plate fixture.

Gel Permeation Chromatography (GPC):

The sample was prepared in Toluene at 0.5% concentration, filtered andanalyzed against PDMS standards using refractive index detection. Thecolumns were two 300 mm Mixed C with a 50 mm guard column. The flow ratewas 1 mL/min.

DSC Experiments

A TA Instruments Q2000 differential scanning calorimeter (DSC) with aliquid nitrogen cooling system (LNCS) was used to measure the glasstransition (T_(g)). A sample of about 10 mg was introduced in a TAInstruments hermetic pan. Indium was used as a calibration standard forheat flow and temperature. Samples were heated at 10° C./min usinghelium as a purge gas (25 mL/min).

Tensile Properties

Stress-strain properties of ionomer siloxanes were obtained by testingdog bone shaped samples in an INSTRON at a 5 mm/min drawing speed.Samples were tested up to failure.

Example 1 Synthesis of Polydimethylsiloxanes (PDMS) Bearing 3.3 mol %Pendant Carboxy Acid Functional Radicals

Reactants:

-   -   PDMS bearing pendant hydrogen groups (SiH) amounting to 3.3 mol        % SiH, more specifically with composition:        (Me₃SiO_(1/2))_(0.017)(MeHSiO_(2/2))_(0.033)(Me₂SiO_(2/2))_(0.95)        where Me is a methyl radical; degree of polymerization (d.p.)        200, steady shear viscosity at 25° C.: η₂₅=0.35 Pa·s; prepared        by methods known in the art such as described in EP 0196169B1    -   Toluene (Fisher Scientific)    -   trimethylsilylated undecylenic acid, prepared as described, for        example, in EP0196169B1    -   Pt on alumina (heterogeneous catalyst, Sigma Aldrich)    -   methanol (Sigma Aldrich)

319.4 g of a PDMS having pendant hydrogen groups (SiH functionality)amounting to 3.3 mol % SiH was loaded to the reaction vessel togetherwith 319.4 g toluene to make a 50% solids solution. A nitrogen blanketwas applied, the mixture was heated to 100° C. and 55 g oftrimethylsilylated undecylenic acid was added. This amounted to a 50 mol% excess of the protected acid (1.5 mol protected acid for 1 mol SiH).1.17 g of a 1 wt % Pt on alumina powder was added, corresponding to 20ppm of Pt based on the sum of SiH functional PDMS, toluene andtrimethylsilylated undecylenic acid. The mixture was heated and kept at100° C. for 2.5 hours. Additional trimethylsilylated undecylenic acid(22.3 g) was introduced in two steps and the reaction temperatureincreased to 110° C. for 6 hours. Infrared analysis indicated completeconversion of the SiH functionality on PDMS. The reaction mixture wasfiltered through a 0.45 m filter. A colorless, clear material wasobtained. The polymer was stripped from solvent and residual unreactedtrimethylsilylated undecylenic acid using a 0.4 mm Hg vacuum at 140° C.To deprotect polymer and convert it to the carboxy acid functionalversion, 336 g of the polymer was added to 224 g of toluene (60 wt %solids solution). 50 g of methanol was added to deprotect the acid underreflux for two hours.

NMR analysis confirmed the expected final structure of the product basedon the SiH PDMS precursor:(Me₃SiO_(1/2))_(0.018)(MeR′SiO_(2/2))_(0.032)(Me₂SiO_(2/2))_(0.95) whereMe is a methyl radical and R′ corresponds to the carboxy acid functionalradical -G-COOH with G corresponding to —(CH₂)₁₀— (based on undecylenicacid).

The material was a clear, color-free, solvent-free low viscosity liquid.Molecular weight and viscosity data on this polymer: M_(w)=28,000 g/mol;M_(n)=8,810 g/mol; η₂₅=0.35 Pa·s

Example 1 Synthesis of Polydimethylsiloxanes Bearing Pendant CarboxyAcid Functional Radicals, Neutralized with Different Levels of LithiumCounter-Ions

The carboxy acid functional PDMS, prepared in example 1, was neutralizedwith Lithium counter-ions (Li⁺) to three different extents: 50%, 75% and100%. In the case of 50%, for example, half of the carboxy acidfunctional radicals are converted with the Li⁺ counter-ion to give—(CH₂)₁₀—COO⁻Li⁺ and half are not converted and remain —(CH₂)₁₀—COOH.Each polymer was neutralized by loading 30 g of the carboxy acidfunctional PDMS with the desired amount of lithium acetylacetonate(Sigma Aldrich) to reach the stated levels of neutralization and 10 g ofmethanol and 20 g of toluene. After mixing for 1 hour at 70° C., thetemperature was increased to 150° C. and vacuum was applied at 15 mbarfor 2 hours to ensure the by-product of neutralization, acetylacetone,was removed while driving the neutralization to completion. Thefollowing materials were obtained.(Me₃SiO_(1/2))_(0.018)(MeR′SiO_(2/2))_(x)(MeR″SiO_(2/2))_(y)(Me₂SiO_(2/2))_(0.95),with R′—(CH₂)₁₀COOH and R″—(CH₂)₁₀—COO⁻Li⁺

TABLE 1 Characteristics of Li⁺ neutralized carboxy acid functional PDMS:(Me₃SiO_(1/2))_(0.018)(MeR′SiO_(2/2))_(x)(MeR″SiO_(2/2))_(y)(Me₂SiO_(2/2))_(0.95)with R′ —(CH₂)₁₀COOH and R″ —(CH₂)₁₀COO⁻Li⁺ Targeted CompositionViscosity neutralization (NMR) Observation at 25° C. at 25° C.  0% x =0.032, clear, low viscosity 0.300 Pa · s y = 0 liquid 50% x = 0.016,clear, high viscosity 14.6 Pa · s y = 0.016 liquid 75% x = 0.008, clear,very high 22,000 Pa · s y = 0.024 viscosity liquid 100%  x = 0, clear,elastic solid gel 1.10⁶ Pa · s* y = 0.032 *value estimated from anoscillatory rheology measurement using small strains

Example 3 Viscoelastic Behavior of Polydimethylsiloxanes Bearing PendantCarboxy Acid Functional Radicals, Neutralized with Different Levels ofLithium Counter-Ions: Illustration of Thermoplastic Elastomeric Behaviorand Control Over the Melt Flow Temperature and Rubbery Plateau Modulus

Insight into the drastic viscoelastic property changes that take placewhen an acid-functional PDMS is neutralized to different extents withLi⁺ can be obtained from small strain shear oscillatory rheologyexperiments, as shown in FIG. 1. Both the storage modulus (G′) and lossmodulus (G″) are shown as a function of temperature are shown. Thestorage modulus relates to the rigidity or stiffness of the material,while the loss modulus is proportional to the amount of energydissipated through heat. The acid-functional PDMS neutralized 100% withLi⁺ counter-ions (curve with x=0, y=0.032), for example following itsrheological profile from low to high temperature, is in the glassy statebelow the glass transition of the PDMS matrix (around −125° C.), passesthrough the glass/rubber transition to a rubbery material extending from−100° C. to room temperature, and enters the melt-flow regime into aviscous liquid beyond this temperature range. This curve indicates oneof the key aspects of the current invention related to thermoplasticelastomers. The metal neutralized PDMS ionomers behave like elastomericrubbers at temperature around room temperature, where energy can bestored and small time-scale deformations to the material are reversible.Once heated to higher temperatures, the thermal break-up of theionomeric interactions reverts the material back to a viscous liquid. Inthis high temperature range, the material behaves like a high molecularweight PDMS polymer.

Reducing the level of neutralization is a convenient method to alter theflow temperature and the temperature range of the rubbery plateaumodulus. Note that the G′ value in the rubbery plateau regime or therubbery plateau modulus is indicative for the cross-link density, whichin case of these ionomeric siloxanes corresponds to the physicalcross-links that form through ionomeric aggregates. This value willrelate to application-related properties like hardness, tack andelasticity.

Example 4 Synthesis of Polydimethylsiloxanes Bearing Pendant CarboxyAcid Functional Radicals, 50% Neutralized with Different MetalCounter-Ions: Impact on Flow Temperature and Rubbery Plateau Modulus

The carboxy acid functional PDMS, prepared in example 1, was neutralizedwith a range of metal counter-ions: metals like Al³⁺ (Aluminumtrivalent, using Aluminum acetylacetonate, Sigma Aldrich), transitionmetals like Zn⁺⁺ (Zinc divalent, using Zinc acetylacetonate, SigmaAldrich), Mn⁺⁺ (Manganese divalent, using Manganese (II)acetylacetonate, Sigma Aldrich), Zr⁴⁺ (Zirconium tetravalent, usingZirconium acetylacetonate, Sigma Aldrich), Mn³⁺ (Manganese trivalent,using Manganese (III) acetylacetonate, Sigma Aldrich), Cr³⁺ (Chromiumtrivalent, using Chromium acetylacetonate, Sigma Aldrich) and alkalimetals like Li⁺ (Lithium monovalent, using Lithium acetylacetonate,Sigma Aldrich, see Example 2). 50% conversion of the carboxy functionalradical was targeted based on the valency of the counter-ion underinvestigation. For example, 50% neutralization with Cr³⁺ corresponded tomixing 0.5/3 mol of the Chromium salt with 1 mol of the —(CH₂)₁₀—COOHfunctionality on PDMS. The procedure was the same for all metalcounter-ions and consisted of loading 30 g of the carboxy acidfunctional PDMS with the desired amount of the metal acetylacetonate toreach the stated levels of neutralization and 10 g of methanol and 20 gof toluene. After mixing for 1 hour at 70° C., the temperature wasincreased to 150° C. and vacuum was applied at 15 mbar for 2 hours. Thismakes sure the by-product of neutralization, acetylacetone, is removedwhile driving the neutralization to completion. Materials weresynthesized so that half of carboxy functional radicals remained withthe other half neutralized with the appropriate metal counter-ion.Materials properties are given in Table 2.

TABLE 2 Characteristics of 50% neutralized carboxy acid functional PDMSbased on(Me₃SiO_(1/2))_(0.018)(MeR′SiO_(2/2))_(0.032)(Me₂SiO_(2/2))_(0.95) withR′ —(CH₂)₁₀—COOH Counter-ion Observation at 25° C. Rubbery plateaumodulus*, Pa Li⁺ clear, high viscosity liquid 45,400 Cr³⁺ clear softcrumbly solid, 6,919 green color Al³⁺ clear, soft crumbly solid 46,854Mn²⁺ clear, high viscosity liquid, 143,000 brown color Mn³⁺ clear, highviscosity liquid, 41,081 dark brown color Zn²⁺ clear, high viscosityliquid 72,278 Zr⁴⁺ clear, rubbery solid 14,405 mg²⁺ clear, rubbery solid278,000 *the rubbery plateau modulus determined as G′ at the minimum intan δ(G″/G′) in a tan δ vs. temperature oscillatory shear rheologyexperiment

As indicated in Table 2, a range of rubbery plateau moduli can beobtained by changing the metal counter-ion. Generally, a higher rubberyplateau modulus results in harder, less tacky materials.

Example 2 Synthesis of a Low Molecular Weight PolydimethylsiloxanesBearing Telechelic Carboxy Acid Functional Radicals and its Li⁺Neutralized Version

To make the endcap or telechelic versions of ionomeric PDMS, thestarting precursor needs to be an SiH terminated PDMS and the procedureoutlined in example 1 and 2 can be used. The procedure used to make a 10mol % telechelic carboxy acid functional PDMS consists of using thefollowing reactants:

-   -   PDMS bearing telechelic hydrogen groups (SiH) amounting to 10        mol % SiH, more specifically DOW CORNING® Q2-5057S (Dow Corning,        Midland, Mich.)    -   toluene (Fisher Scientific)    -   trimethylsilylated undecylenic acid, prepared as described, for        example, in EP0196169B1    -   Pt on alumina (heterogeneous catalyst, Sigma Aldrich)    -   methanol (Sigma Aldrich)        150 g of a PDMS having telechelic hydrogen groups (SiH        functionality) amounting to 10 mol % SiH was loaded to the        reaction vessel together with 150 g toluene to make a 50% solids        solution. A nitrogen blanket was applied, the mixture was heated        to 90° C. and 60.53 g of trimethylsilylated undecylenic acid was        added. This amounted to a 4 mol % excess of the protected acid        (1.04 mol protected acid for 1 mol SiH). 0.72 g of a 1 wt % Pt        on alumina powder was added, corresponding to 20 ppm of Pt based        on the sum of SiH functional PDMS, toluene and        trimethylsilylated undecylenic acid. The mixture was heated and        kept at 100° C. for 1 hour. Infrared analysis indicated no        residual SiH after this step. The reaction mixture was filtered        through a 0.22 m filter. A colorless, clear material was        obtained. The polymer was stripped from solvent and residual        unreacted trimethylsilylated undecylenic acid using a 0.4 mm Hg        vacuum at 140° C. To deprotect the polymer and convert it to the        carboxy acid functional version, 150 g of the polymer was added        to 100 g of toluene (60 wt°/0 solids solution). 100 g of        methanol was added to deprotect the acid under reflux for two        hours. The final material was stripped from solvent on a rotary        evaporator at 150° C. and 0.8 mmHg for 1 hour.

NMR analysis confirmed the expected final structure of the product basedon the SiH PDMS precursor:(Me₂R′SiO_(1/2))_(0.103)(Me₂SiO_(2/2))_(0.897) where Me is a methylradical and R′ corresponds to the carboxy acid functional radical—(CH₂)₁₀—COOH. The material was a clear, color-free, solvent-free lowviscosity liquid.

The Li⁺ 100% neutralized version of the 10.3 mol % carboxy acidfunctional PDMS material was obtained by loading 50 g of the PDMSprecursor into 35 g toluene, 15 g methanol and adding 5.907 g Lithiumacetylacetonate stoichiometrically. The reaction mixture was heated to80° C. for 1 h. The polymer solution was stripped from solvent on arotary evaporator at 155° C. and 0.8 mmHg for 2.5 h. The final materialwas a colorless, hard solid at room temperature.

Example 6 Synthesis of High Molecular Weight Polydimethylsiloxanes(M_(w)=100,000 g/mol) Bearing 1 Mol % Telechelic Carboxy Acid FunctionalRadicals, 100% Neutralized With Mg++Counter-Ions or 100% Neutralizedwith Li⁺ Counter-Ions

The telechelic version of ionomeric PDMS with high molecular weight andconsequently low carboxy acid functionality started from the SiHterminated precursor and follows a procedure similar to example 5. Theprocedure used to make a 1 mol % telechelic carboxy acid functional PDMSused the following reactants:

-   -   PDMS bearing telechelic hydrogen groups (SiH) amounting to 1.3        mol % SiH, more specifically with composition:        (Me₂HSiO_(1/2))_(0.013)(Me₂SiO_(2/2))_(0.987) where Me is a        methyl radical; degree of polymerization (d.p.) is about 1,000        (see example 1 for specifics on SiH precursors);    -   toluene (Fisher Scientific)    -   trimethylsilylated undecylenic acid, prepared as described, for        example, in EP0196169B1    -   Pt on alumina (heterogeneous catalyst, Sigma Aldrich)    -   methanol (Sigma Aldrich)        175 g of a PDMS having telechelic hydrogen groups (SiH        functionality) amounting to 1.3 mol % SiH was loaded to the        reaction vessel together with 61 g toluene to make a 74% solids        solution. A nitrogen blanket was applied, the mixture was heated        to 100° C. and 8.27 g of trimethylsilylated undecylenic acid was        added. This amounts to a 5 mol % excess of the protected acid        (1.05 mol protected acid for 1 mol SiH). 0.49 g of a 1 wt % Pt        on alumina powder was added, corresponding to 20 ppm of Pt based        on the sum of SiH functional PDMS, toluene and        trimethylsilylated undecylenic acid. The mixture was heated and        kept at 100° C. for 1 hour. Infrared analysis indicated very        little residual SiH after this step. The reaction mixture was        filtered through a 0.22 m filter. A colorless, clear material        was obtained. To deprotect the polymer and convert it to the        carboxy acid functional version, 40 g of methanol was added. The        mixture was heated at reflux for 2 hours. The final material was        stripped from solvent on a rotary evaporator at 150° C. and 0.8        mmHg for 1 hour.

NMR analysis confirmed the expected final structure of the product basedon the SiH PDMS precursor:(Me₂R′SiO_(1/2))_(0.013)(Me₂SiO_(2/2))_(0.987) where Me is a methylradical and R′ corresponds to the carboxy acid functional radical—(CH₂)₁₀—COOH. The material was a clear, color-free, solvent-free lowviscosity liquid.

The Li⁺ 100% neutralized version of the 1.3 mol % carboxy acidfunctional PDMS material was obtained by loading 50 g of the PDMSprecursor into 35 g toluene, 15 g methanol and adding 0.833 g Lithiumacetylacetonate stoichiometrically. The reaction mixture was heated at80° C. for 1 hour. The polymer solution was stripped from solvent on arotary evaporator at 170° C. and 0.6 mmHg for 2 hours. The finalmaterial was a colorless, extremely high viscosity liquid at roomtemperature.

The Mg⁺⁺ 100% neutralized version of the 1.3 mol % carboxy acidfunctional PDMS was made similarly by adding magnesium acetylacetonate(Sigma Aldrich) stoichiometrically to the carboxy acid precursor.

A comparison between the low molecular weight/high ion containing Li⁺neutralized ionomer from Example 5 and the high molecular weight/low ioncontaining Li⁺ neutralized ionomer from Example 6 is given in Table 3.It is clear from this analysis that the ion content dominates therheology behavior, since the highest rubbery plateau modulus and flowtemperature is found for the 10 mol % ionomer, which has the lowestmolecular weight. From a rheological perspective, the highest ioncontaining polymer self-assembles into a much higher effective molecularweight or cross-link density than its low ion counter-part. Whencompared to the results in Example 4 on the effect of counter-ion type,the telechelic ionomers based on one counter-ion type but different ioncontents can have some advantages if material properties at roomtemperature (rubbery plateau modulus) and flow temperatures need to beoptimized, for example, for a hot melt application, without changing themetal counter-ion used. Basically, these two procedures to alter theproperties of PDMS-based ionomers offer flexibility in materials design.

TABLE 3 Characteristics of 100% Li⁺ neutralized telechelic carboxy acidfunctional PDMS: high M_(w)/low ion content (1.3 mol %, Example 6) andlow M_(w)/high ion content (10 mol %, Example 5) Rubbery plateau FlowIon content Observation modulus*, temperature**, (—(CH₂)₁₀—COO⁻Li⁺) at25° C. Pa ° C. 1.3 mol % clear, extremely 217,000 120 high viscosity  10mol % clear, hard solid 9,380,000 160 *rubbery plateau modulusdetermined as G′ at the minimum in tan δ (G″/G′) in a tan δ vs.temperature oscillatory shear rheology experiment **flow temperature, asdetermined from the temperature at which G′ reaches 1 kPa upon heating

Example 7 Comparison Between a High Molecular WeightPolydimethylsiloxanes (M_(w)=100,000 g/mol) Bearing 1 Mol % Carboxy AcidFunctional Radicals, 100% Neutralized with Mg⁺⁺ Counter-Ions and aChemically Cross-Linked PDMS Rubber

A comparison is made between an ionomeric PDMS with physical cross-linksand a chemically cross-linked PDMS rubber as far as rheology andmechanical properties. To compare these systems side-by-side, a similarcross-link density is targeted for both materials. This was achieved byselecting the vinyl-functional PDMS and SiH cross-linker for thechemically cross-linked PDMS rubber appropriately. To check the level ofcross-link density, either physical or chemical, the rubbery plateaumodulus was used, since this value can be used to calculate themolecular weight between cross-links, M_(C), regardless of the chemistryused:M _(C) =ρ.R.T/G ^(N) ₀with: M_(C) the molecular weight between cross-links, ρ the density, Rthe gas constant, T the temperature and G^(N) ₀ the rubbery plateaumodulus. The following two materials were compared in this manner:

-   -   1. 100% Mg⁺⁺ neutralized 1 mol % carboxy acid functional PDMS        from example 7.    -   2. vinyl-functional PDMS cured with an SiH cross-linker using a        Pt catalyst, based on the following formulation:        -   170 g DOW CORNING® SFD-117 Filtered Fluid (Dow Corning,            Midland Mich.) a vinyl-containing polymer (d.p. 434), 30 g            DOW CORNING® 2-7220 INTERMEDIATE a SiH cross-linker (Dow            Corning, Midland Mich.), and 20 ppm of a Pt catalyst DOW            CORNING® 2-0707 INT (PLATINUM 4) (Dow Corning, Midland            Mich.) (0.56% Pt) was used in combination with 0.5 wt % of            2-methyl-3-butyn-2-ol inhibitor (Sigma Aldrich) to cure the            rubber at 50° C. over 24 hours. The polymer, cross-linker            and inhibitor were mixed together at room temperature and            introduced in a vacuum oven at room temperature to get the            bubbles out. The Pt catalyst was added to this mixture and            the sample was introduced in an air evacuated oven at 50° C.            for 2 days to fully cure the elastomer.            The rubbery plateau modulus values are similar for both            materials as summarized in Table 4. The effective cross-link            density of both materials must therefore be similar in a            temperature range below 150° C. where the ionomer starts to            flow. Note that the chemically cross-linked PDMS rubber            doesn't exhibit flow at any temperature below its            degradation temperature.

TABLE 4 Characteristics of 1. PDMS ionomer: 100% Mg⁺⁺ neutralizedtelechelic carboxy acid functional PDMS: high M_(w)/low ion content (1.3mol %, Example 6) compared to 2. PDMS rubber: a chemically cross-linkedPDMS rubber Rubbery Observation at plateau Flow temperature**, Material25° C. modulus*, Pa ° C. PDMS ionomer clear, elastic solid 133,000 150PDMS rubber clear, elastic solid 190,000 n/a*** *rubbery plateau modulusdetermined as G′ at the minimum in tan δ (G″/G′) in a tan δ vs.temperature oscillatory shear rheology experiment **flow temperature, asdetermined from the temperature at which G′ reaches 1 kPa upon heating***chemically cross-linked elastomeric rubber does not flow at anytemperature

To confirm the similarity in mechanical properties between the PDMSrubber and its ionomeric counterpart, FIG. 2 compares the tensileproperties at room temperature. Both the tensile strength (around 50psi=350 kPa) and strain at break (around 180%) are similar.

Example 8 Blends of PDMS Ionomers with Different Ion Contents

Two PDMS ionomers were blended to illustrate the level of propertycontrol that can be achieved by modifying the physical cross-linkdensity. Two benefits are obtained simultaneously which are difficult toachieve with a chemically cross-linked PDMS:

1) The PDMS ionomers form miscible, transparent blends over a widecomposition range. This is in part due to their identical chemicalconstituents, even though the ion content might differ.

2) There is no issue with stoichiometric imbalance since the physicalcross-link points are formed from the aggregation of one type offunctionality, e.g. COO⁻Li⁺. This is in contrast to a vinyl/SiH curedPDMS, for example, where higher cross-link densities would require boththe vinyl and SiH content to be increased if no stoichiometric imbalanceis acceptable.

A telechelic PDMS ionomer with high ion content, detailed in example 5(10 mol % COO⁻Li⁺ PDMS ionomer), was blended with a pendant PDMS ionomerwith low ion content (1.9 mol % COO⁻Li⁺ ionomer) similar to the onedetailed in Example 2. Although the inventors do not want to be held toone theory, it is believed, that the low ion content, high molecularweight PDMS ionomer with low ion content forms the bulk of the materialand introduces some entanglement strength to the blends' properties. Thelow molecular weight, high ion content PDMS ionomer can be considered tobe a physical cross-linker, linking sites of the high molecular weightionomer through ionic aggregates.

The blending procedure consisted of introducing the appropriate amountsof each ionomer into a 9/1 mixture of toluene to methanol to make a 20%solids solution. A rotating mixing wheel was used for 10 hours to ensurecomplete dissolution. Mixtures were introduced on Teflon films and heattreated using the following step-wise profile: 1 hour at 80° C., 1 hourat 100° C., 20 min at 150° C. Samples were allowed to cool to roomtemperature slowly. Table 5 contains the details on the effect of blendratio on rheological properties. All the samples were transparent solidfilms at room temperature. The table shows that a range of rubberyplateau moduli and flow temperatures can be accessed simply by blendingtwo PDMS ionomers. This adds materials design flexibility since only twomaterials have to be synthesized while a blend can be made to reach acertain targeted behavior.

TABLE 5 Characteristics of ionomer blends based on A) a 100% Li⁺neutralized telechelic carboxy acid functional PDMS: low M_(W)/high ioncontent (10 mol %, example 5) and B) a 100% neutralized pendant carboxyacid functional PDMS: high M_(W)/low ion content (1.9 mol %, similar toExample 2) Rubbery Flow Ratio plateau temperature**, A/B Observation at25° C. modulus*, Pa ° C. 1/0 clear, hard solid, non-tacky 9,380,000 1603/7 clear, rubbery solid, slight tack 4,220,000 158 2/8 clear, rubberysolid, slight tack 2,980,000 154 1/9 clear, rubbery solid, slight tack2,000,000 146 0/1 clear, flexible, tacky solid 1,000,000 137 *rubberyplateau modulus determined as G′ at the minimum in tan δ (G″/G′) in atan δ vs. temperature oscillatory shear rheology experiment **flowtemperature, as determined from the temperature at which G′ reaches 1kPa upon heating

Example 9 Synthesis of Resin-Linear Materials

An additional level of control over material properties andcompatibility can be achieved by modifying the base siloxane, either byincorporating branching or introducing phenyl modification. Branchingwill dramatically raise the glass transition of the siloxane polymer,which is around −125° C. for PDMS-based ionomers. Phenyl modificationwill also raise the glass transition but, more importantly, improvecompatibility with organic matrices like epoxides, polyesters,acrylates, etc. . . . A phenyl-modified, branched siloxane ionomer withthe following composition was targeted:

(MeR′SiO_(2/2))_(0.09)(MeR″SiO_(2/2))_(0.81)(R″SiO_(3/2))_(0.10)

with R′—(CH₂)₁₀—COOH and R″ a phenyl radical.

A different procedure was used in this case, even though hydrosilylationwith trimethylsilylated undecylenic acid could also be employed in thiscase. More information on the procedure which starts from anamine-functional precursor and uses itaconic acid to convert into acarboxy-functional material, can be found in Berger A.; Fost D. L. U.S.Pat. No. 5,596,061; 1997, Organosilicone having a carboxyl functionalgroup thereon. Hydrolysis and condensation of the followingalkoxysilanes will result in the targeted building blocks:

-   -   phenylmethyldimethoxy silane (DOW CORNING® Z-2588        Phenylmethyldimethoxy Silane) 597.9 g (3.28 mol)    -   aminopropyl methyl diethoxysilane (DOW CORNING® Z-6015 Silane)        61.2 g (0.32 mol)    -   phenyltrimethoxysilane (DOW CORNING® Z-6124 Silane) 79.3 g (0.4        mol)        Other reactants/catalysts that were used:    -   xylenes (Sigma Aldrich)    -   de-ionized water    -   potassium hydroxide (1 N KOH aq, Sigma Aldrich)    -   hydrochloric acid (1 N HCl aq, Sigma Aldrich)    -   itaconic acid (Sigma Aldrich)        A reaction vessel was loaded with the alkoxysilanes and heated        to 50° C. 9.56 mL of 1N KOH was added followed by 151.4 g of        de-ionized water (amounts to twice the stoichiometric amount).        The temperature was raised to 73° C. for 30 min. 536 g of        xylenes were added. The volatiles were distilled off up to a        reaction temperature of 85° C. The aqueous phase was removed and        the reaction mixture was cooled to 50° C. 9.56 mL of 1N HCl was        added to neutralize the KOH and stirring was applied for 1 h at        25° C. The mixture was heated to reflux and water was removed by        azeotropic distillation. After cooling the reaction mixture to        85° C., 44.05 g itaconic acid was added, which corresponds to a        5 mol % excess to the amine (—NH₂) groups. The reaction mixture        was heated to reflux for 3 hours and water was again removed        using azeotropic distillation. The final product was stripped        from solvent on a rotary evaporator at 150° C. using 0.5 mmHg        vacuum for 1 h. The product was a solvent-free, clear,        orange-color viscous liquid at room temperature. The composition        of the final material as confirmed by        NMR:(MeR′SiO_(2/2))_(0.093)(MeR″SiO_(2/2))_(0.799)(R″SiO_(3/2))_(0.10)        with R′—(CH₂)₁₀—COOH and R″ a phenyl radical

To prepare the metal neutralized versions of the carboxy-functionalbranched phenyl siloxane ionomer, the polymer was dissolved in a 6/4toluene/methanol mixture at 40 wt % polymer solids. The appropriatemetal acetylacetonate was introduced at the targeted stoichiometry andthe reaction mixture was heated to 85° C. for 1 hour with mixing. Themetal neutralized carboxy-functional siloxane was stripped from solventon a rotary evaporator at 160° C. and 0.6 mmHg vacuum for 1 hour.

A range of metal counter-ions were used to prepare 100% neutralizedversions of the carboxy-functional branched phenyl siloxane ionomer,resulting in the properties listed in Table 6.

TABLE 6 Characteristics of metal neutralized branched phenyl siloxaneionomers based on(MeR′SiO_(2/2))_(0.093)(MeR″SiO_(2/2))_(0.799)(R″SiO_(3/2))_(0.10) withR′ —(CH₂)₁₀—COOH and R″ a phenyl radical Rubbery plateau Flow GlassCounter- Observation modulus*, temperature**, transition***, ion at 25°C. Pa ° C. ° C. Zn²⁺ clear, tacky n.a. 41 0 solid, flows over time Na⁺clear, tacky 417,000 55 −2 solid, some elasticity Li⁺ clear, tacky327,000 81 −3 solid, doesn't flow Mg²⁺ clear, slightly 5,380,000 142 −2tacky Ca²⁺ clear, tacky 4,000,000 160 −1 solid Cu²⁺ clear, crumbly2,590,000 155 0 solid, elastic Ni²⁺ clear, crumbly 1,560,000 200 2 solid*rubbery plateau modulus determined as G′ at the minimum in tan δ(G″/G′) in a tan δ vs. temperature oscillatory shear rheology experiment**flow temperature, as determined from the temperature at which G′reaches 1 kPa upon heating ***glass transition as measured byoscillatory shear rheology as the maximum in tan δ vs. temperature

The results in Table 6 indicate the wide range of properties that areaccessible starting from the same carboxy-functional precursor. Thesematerials are prime candidates for hot melt applications that can relyboth on the increased matrix glass transition (around 0° C. in Table 6)and the selection of counter-ion to meet certain melt flowspecifications (melt flow temperatures from 41° C. up to 200° C. inTable 6). The tensile properties listed in Table 7 indicate that thesematerials also hold promise as elastomeric rubbers.

TABLE 7 Tensile properties of a Li⁺ and Mg²⁺ neutralized branched phenylsiloxane ionomer based on(MeR′SiO_(2/2))_(0.093)(MeR″SiO_(2/2))_(0.799)(R″SiO_(3/2))0.10 with R′—(CH₂)₁₀—COOH and R″ a phenyl radical Counter-ion Tensile strength, MPaStrain at break, % Li⁺ 1.65 48 Mg²⁺ 25 12

Example 10 Blends of PDMS Ionomers with MQ Resins as Hot Melt Materials

PDMS-based ionomers can be mixed with trimethylated silica particles (inshort MQ resins) to obtain miscible blends with modified rheologicalbehavior. In particular, the addition of MQ resin raises the glasstransition and lowers the rubbery plateau modulus. The difference withthe procedure used in Example 9 is that the MQ/PDMS ionomer blends donot rely on branching or phenyl incorporation to attain higher matrixglass transitions. In contrast, the presence of nano-scale MQ particlesalters the PDMS polymer dynamics. As an example, a 50% Al³⁺ neutralizedPDMS ionomer (based on(Me₃SiO_(1/2))_(0.018)(MeR′SiO_(2/2))_(0.032)(Me₂SiO_(2/2))_(0.95) withR′—(CH₂)₁₀—COOH see Example 4) was used as the host polymer, modifiedwith different levels of MQ resin (DOW CORNING® 5-7104 INT). A 50%solids solution was made of the ionomer and MQ resin in toluene/methanol(99/1 wt/wt) as a solvent. After mixing overnight, thin films were castand stripped of solvent at 150° C. for 1 h and 180° C. for 30 min. Allblends were transparent solids at room temperature. This indicates thatMQ is fully miscible with the 50% Al³⁺ neutralized PDMS ionomer in thecomposition range tested. Results are shown in Table 8.

TABLE 8 Characteristics of 50% Al³⁺ neutralized PDMS ionomers blended indifferent ratios with MQ resin Rubbery ionomer/MQ plateau Flow Glass(wt/wt) modulus*, Pa temperature**, ° C. transition***, ° C. 1/0 45,384109 −116 7/3 27,350 108 −94 6/4 18,600 77 −70 5/5 n.a.**** 78 −63 4/6n.a.**** 120 n.a. *rubbery plateau modulus determined as G′ at theminimum in tan δ (G″/G′) in a tan δ vs. temperature oscillatory shearrheology experiment **flow temperature, as determined from thetemperature at which G′ reaches 1 kPa upon heating ***glass transitionas measured by oscillatory shear rheology as the maximum in tan δ vs.temperature ****the rheological profile doesn't exhibit a rubberyplateau modulus due to the proximity of the flow temperature to theglass transition

The advantage of using MQ resin as opposed to branching and phenylincorporation for a hot melt application would be that MQ/PDMS blendsare already used in this application and a lot of the beneficialproperties of MQ/PDMS blends would be retained with the added controlintroduced by the ionomeric aggregates regarding faster solidificationupon cooling and control over melt flow temperature. Therefore, PDMSionomer could extend the application window of hot melt materials.

Example 11 PDMS Ionomers for Use in Gellants for Cosmetic Applications

The purpose of this evaluation was to use siloxane ionomers astransparent thickeners for cosmetic applications. An example would be astick antiperspirant containing a large (75%) amount of carrier fluid.The 10 mol % Li⁺ neutralized siloxane ionomer from example 4 was used.Before stripping the solvent after synthesis of the metal neutralizedionomer, a cosmetic carrier with high boiling point was added and theoriginal solvent was removed by a solvent exchange procedure.Cyclosiloxanes were used as the carrier (DOW CORNING® 246 Fluid), forexample, and a 1 hour stripping step at 100° C., 100 mmHg was sufficientto remove the original solvent (toluene) and retain the carrier. In thisway, the 10 mol % Li⁺ neutralized siloxane ionomer was swollen by thecyclosiloxanes to form a homogeneous, soft, clear gel.

That which is claimed is:
 1. A thermoplastic elastomer comprising atleast one silicone ionomer having an average Formula (1)(X_(v)R_(3-v)SiO_(1/2))_(a)(X_(w)R_(2-w)SiO_(2/2))_(b)(X_(y)R_(1-y)SiO_(3/2))_(c)(SiO_(4/2))_(d)where each R is an independently selected monovalent alkyl group or arylgroup, each X is independently selected from a monovalent alkyl group,aryl group and a carboxy functional group having a Formula (2) -G-COOZ,where G is a divalent spacer group having at least 2 spacing atoms, eachZ is independently selected from hydrogen or a cation independentlyselected from alkali metal cations, alkali earth metal cations,transition metal cations, and metal cations, v is 0 to 3, w is 0 to 2, yis 0 to 1, 0≦a≦0.9; 0≦b<1; 0≦c<0.9, 0≦d<0.3 and a+b+c+d=1, provided thaton average there is at least 0.002 mole carboxy functional groups persilicon atom and at least 10 mole percent of the Z groups of the carboxyfunctional group are an independently selected cation.
 2. Thethermoplastic elastomer of claim 1 where at least 50 mole percent of theZ groups of the carboxy functional group are an independently selectedcation.
 3. The thermoplastic elastomer of claim 1 where at least 75 molepercent of the Z groups of the carboxy functional group are anindependently selected cation.
 4. The thermoplastic elastomer of claim 1where 100 mole percent of the Z groups of the carboxy functional groupare an independently selected cation.
 5. The thermoplastic elastomer ofclaim 1 where the cation is selected from a group consisting of Li, Na,K, Cs, Mg, Ca, Ba, Zn, Cu, Ni, Ga, Al, Mn, and Cr.
 6. The thermoplasticelastomer claim 1 where the cation is selected from the group consistingof Li, Na, K, Zn, Ni, Al, Mn, and Mg.
 7. The thermoplastic elastomer ofclaim 1 where on average there are at least 0.01 mole carboxy functionalgroups per silicon atom.
 8. The thermoplastic elastomer of claim 1 whereon average there are at least 0.02 mole carboxy functional groups persilicon atom.
 9. The thermoplastic elastomer of claim 1 where on averagethere are from 0.002 to 0.5 mole carboxy functional groups per siliconatom.
 10. The thermoplastic elastomer of claim 1 comprising a blend ofat least two silicone ionomers.
 11. The thermoplastic elastomer of claim1 further comprising an MQ resin.
 12. The thermoplastic elastomer ofclaim 1 further comprising filler.